Happy or beautiful. Something like alcest without the blackmetal guitars or John Butler. This will be interesting.

bjork comes to mind

aphex twin can be also quite joyous, i have the richads d. james, and i listen to it, when tired of metal
usually go for electro stuff, like meat beat manifesto

Gruff Rhys - Candylion. Heard it once and liked it. Makes me sick with 'happyness' and 'sweetness' usually.

jääportit or nest

If you don't care about genre listen to Polysics!

[Keeker]

Chuck Berry - My Ding-a-Ling

Makes me sick with 'happyness' and 'sweetness' usually.

I'm not after that bunnies and flowers type of happiness. More like the dreamy feeling in alcest.

I've actually never liked sad or meloncholy music. Most of my (metal)friends, listen to Katatonia, My Dying Bride, Anathema, Type O Negative... All real downer stuff. I hate all that.
I'm much more into the 'major' melodies and harmonies.
Bad Religion springs to mind, a lot of punk bands have uplifting and happy melodies (No Fun At All, NoMeansNo, etc). Try to find major-based songs; unfortunately you'll find out that most of these happy songs can be found in genres you would never listen too, like dance music, or bands like Oasis or Blur.
Japanese music also has a lot of happy tunes, sometimes a bit weird though.
Rock-opera stuff, like Ziltoid and Ayreon; Weird Al Yankovic, Frank Zappa, etc.

Sigur Ros
Explosions in the Sky
Violent Femmes
Album Leaf

listen to editors, engineers, the magnetic fields, múm, gåte, tori amos (her happy songs at least), and whatnot

it is difficult to find "happy" in metal. so broaden your horizons, dang it!

Tenacious D.

Oooooohhh yeah.

Sounds like you wanna listen to Sigur Ros. And if you don't you should.

Paul Simon

Sigur Ros for sure.

at the risk of offending some bearded metal heads:

bob marley and the wailers?
presidents of the united states of america?
rhcp?
dennis brown?
jimi hendrix?